What is the water quality grade for Old Reservoir?

Old Reservoir in Randolph County, Wisconsin received a water quality grade of C (Fair). Water clarity: 3.6 ft visibility. Phosphorus: 33 µg/L. Chlorophyll-a (algae): 14.2 µg/L. Surface area: 21 acres.

Is Old Reservoir safe to swim in?

Generally safe for swimming, moderate water quality. Old Reservoir has an overall water quality grade of C. Algae concentration (chlorophyll-a) is 14.2 µg/L. Always check local health department advisories before swimming.

Old Reservoir

Randolph County, WisconsinEutrophic

Old Reservoir is a 21-acre productive, nutrient-rich eutrophic lake in Randolph County, MO. Water quality is graded C based on 3 sampling years through 2024. Compared to the 6 other monitored lakes in Randolph County, Old Reservoir ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-09-17. Grade methodology: LakeGrade methodology.

Swimming Safety

Generally safe for swimming, moderate water quality

Water Quality Grade: C, Fair

Murky, only visible to about 3.6 ft. Phosphorus level: 33 µg/L. Chlorophyll-a: 14.2 µg/L. Trophic State Index: 57.

Metric	Value	Grade
Water Clarity (Secchi Depth)	3.6 ft	D
Phosphorus	33 µg/L	C
Chlorophyll-a (Algae)	14.2 µg/L	C
Trophic State Index (TSI)	57	Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

Characteristic	Value
Surface Area	21 acres

Location

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County Ranking

Ranked #1 of 7 lakes in Randolph County

Nearby Lakes in Randolph County

Thomas Hill Res. Nr. Dam Lake

Randolph County

Sugar Creek Lake North Arm

Randolph County

More Wisconsin Lake Rankings

Cleanest lakes in Wisconsin

Top 25 by overall water quality score

Best swimming lakes in Wisconsin

Grade A/B + low algae filter

Family fishing lakes in Wisconsin

Panfish-rich, public access

All Wisconsin lakes

Full state directory

Other Grade C Lakes in Wisconsin

Aspen Lake Along Southern Arm

Warren County · Clarity: 3.8 ft

Mark Twain Lake by Hwy J

Ralls County · Clarity: 3.7 ft

Red Fox Lake

Warren County · Clarity: 3.3 ft

Waukomis Lake

Platte County · Clarity: 4.7 ft

Table Rock L. Nr. Greens Hollow Lake

Barry County · Clarity: 5 ft

Little Prairie Lake by Dam

Phelps County · Clarity: 4.9 ft

Eutrophic Lakes in Wisconsin

Aspen Lake Along Southern Arm Boathouse Lake Hunnewell Lake Long Branch Lk. Lake

Reservoir Info (USACE NID)

Old Reservoir is a man-made reservoir impounded by the Water Works Lake Dam (completed 1870), built primarily for recreation on the TRIBUTARY TO SWEET SPRING CRK; earth-type dam, 30 ft tall.

Surface area: 21 ac
Normal storage: 147 ac-ft
Max storage: 337 ac-ft
Drainage area: 418 sq mi
Hazard class: High
Owner: MOBERLY-PARKS&RECREATION

All listed purposes: Recreation;Water Supply.

Source: USACE National Inventory of Dams, NID ID MO10006 · Operator website · Matched by proximity (0.04 km)

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2024-09-17

Monitoring stations: 1